Fiat tc intake manifold

[so cal mark]

Hi Guy
I was wondering if you had done any flow testing on the oem 1800 intake manifolds? I'm curious if the two end runners flow differently than the middle two runners?
I have a tc I'm working on that has exhaust temps over 100f hotter on the two end runners than on the middle two. Timing doesn't seem to have any effect on the temps.

[Guy Croft]

Hello Mark

sorry, behind here because of Xmas hols, I will do some tests on one I'm engaged with for CKL Dec Ltd for a 1438 TC racer during Jan, please drop me an e-mail to remind me to post results for your benefit.

I can certainly confirm right now that cyl 4 is very much at risk (compared with to 1,2,3) from detonation - on carburetted engines.

This is due to poor fuelling quality (high inlet air temp, poor atomisation and cylinder filling problems mainly emanating from manifold wetted area and length of inlet tract), and on top of that cylinder (4) is furthest from the water pump and outlet elbow and thus the hottest.
The fuel injected engines don't have that problem - ever.

GC

[so cal mark]

Guy, thanks for the response. Since my post I've been doing some road testing with a thermocouple attached to the header tubes. I've found some interesting results, with the peak temps occuring at 3500-4000 rpm with light throttle rather than acceleration. Adding timing advance brings the temp down substantially in that range also. I have found #4 runs the hottest, and have tried jetting a little richer to compensate.
Have you used a carb spacer to try to even out flow thru the manifold at all?